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arXiv · astro-ph/0303400

Model-Independent Reionization Observables in the CMB

Wayne Hu·Gilbert P. Holder
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Abstract

We represent the reionization history of the universe as a free function in redshift and study the potential for its extraction from CMB polarization spectra. From a principal component analysis, we show that the ionization history information is contained in 5 modes, resembling low-order Fourier modes in redshift space. The amplitude of these modes represent a compact description of the observable properties of reionization in the CMB, easily predicted given a model for the ionization fraction. Measurement of these modes can ultimately constrain the total optical depth, or equivalently the initial amplitude of fluctuations to the 1% level regardless of the true model for reionization.

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Wayne Hu, Gilbert P. Holder. 2003-03-18. Model-Independent Reionization Observables in the CMB. https://doi.org/10.1103/physrevd.68.023001

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